Why IPM Selection Deserves Care

An intelligent power module puts the whole inverter stage, the gate drivers and the protection in one package, so a designer can build a compact motor drive with a small external circuit. Choosing the right voltage and current rating and planning the heat sink decides the reliability of the drive. This guide walks through a repeatable method for selecting a BYD Semiconductor intelligent power module.

Step 1: Fix the Voltage Class

Start with the AC input and the rectified bus. A 600 V class module suits a single-phase or a three-phase mains up to about 240 V AC with the usual margin for the rectified bus and the switching overshoot. Confirm the class against the worst-case bus, including the line regulation and the transient, because too little margin shortens the life and too much wastes the loss. The BYD IPM range is built around the 600 V class for mains-fed motor drives.

The Rectified Bus

A single-phase front end gives a bus of about 310 V DC from a 220 V AC line, and a three-phase front end a bus of about 530 V DC from a 380 V AC line, before the overshoot. The module must sustain the bus plus the overshoot, so the class is chosen with that in mind, and the 600 V class covers a single-phase drive with good margin.

Step 2: Size the Current

The current rating is set by the RMS phase current of the motor, which depends on the load and the power factor, not by the peak alone. Compute the RMS current, add margin for the overload and the start-up, and check the rating at the expected case temperature, because the current capability is a thermal limit. A BYD IPM covers 10 A, 15 A and 30 A, so a fan, a pump and an appliance compressor each have a good fit. Keep the module within the rating for the ambient so the protection does not trip and the life is not shortened.

Loss and Efficiency

The module loss is the conduction loss plus the switching loss, and it sets the heat that the heat sink must remove. A lower switching frequency reduces the switching loss, and a good modulation reduces the conduction loss, so the operating point and the control scheme matter as much as the module. Confirm the loss at the real current and frequency.

Step 3: Match the Package and the Heat Sink

Choose the package for the board and the heat sink, and plan the thermal path together with it. The BYD IPM comes in packages such as the DIP-27 and BIP27 that mount on a heat sink, and the power pins and the control pins are separated for the layout. Compute the module loss, choose the heat sink and the interface from the thermal resistance, and confirm the case temperature at the worst-case ambient. Measure it on the bench before you release the design.

The Bootstrap and the Gate Drive

The module contains the high-side gate drive and the bootstrap diodes, so the designer only needs to provide the low-voltage control supply and the bootstrap capacitor. Keep the bootstrap capacitor close to the module and the control supply clean, because a poor bootstrap supply is a common cause of a fault at high duty.

Step 4: Plan the Protection and the Current Sense

The module includes under-voltage lockout and over-current protection and provides a fault output, so connect the fault to the controller and use it to shut the drive down safely. The current sense is usually a shunt in the DC link or the low-side legs, and its signal feeds the over-current comparator and the controller's ADC. Choose the shunt value for the trip current you need, keep the connection short and confirm the trip against the motor and the module rating.

Getting Help

If you send your mains voltage, motor current, control method and thermal environment to our FAE team, we will propose a module, help choose the rating and the heat sink and review the protection and the layout. BeiLuo holds mainstream BYD IPMs in regional stock and ships them with an import declaration, a certificate of origin and a RoHS compliance file, and our engineers will review the choice with you before you commit to production.